The present invention relates to an electrical apparatus for generation, transmission, distribution and/or usage of electrical energy, comprising a housing enclosing an electrical apparatus interior space, at least a portion of which forms at least one insulation space having an electrical component and containing a surrounding insulation medium comprising an amount of carbon dioxide mco2. The insulation space is formed by at least one insulation space compartment, in which an adsorber for reducing or eliminating the amount of water mH2O and optionally further contaminants from the insulation medium is arranged. The amount of adsorber mads arranged in the at least one insulation space compartment complies with the formulae (I) and (II). m ads ≥ m H 2 ⁢ O k ads , H 2 ⁢ O ( I ) m ads ≤ 0.1 ⁢ m CO 2 k ads , CO 2 ( II )